This paper provides a comprehensive review of piezoelectric energy-harvesting techniques developed over the past decade, focusing on methodologies that lead to high power output and broad operational bandwidth. The piezoelectric effect is widely used to convert mechanical energy into electrical energy due to its high energy conversion efficiency, ease of implementation, and miniaturization. The review covers various designs, nonlinear methods, optimization techniques, and harvesting materials, with a focus on four promising applications: shoes, pacemakers, tire pressure monitoring systems, and bridge and building monitoring. The paper also discusses the challenges and future directions in energy harvesting, emphasizing the need for reliable and system-integrated solutions. Nonlinear methods, such as bistable and tristable systems, are explored to extend the operational bandwidth and enhance power output. Additionally, the paper reviews new structures and materials that improve power output, including geometry-modified cantilevers, topology optimization, curved structures, electrode optimization, and new structures operating under tension or compression excitations. The goal is to guide future research and promote the practical application of piezoelectric energy harvesters in various fields.This paper provides a comprehensive review of piezoelectric energy-harvesting techniques developed over the past decade, focusing on methodologies that lead to high power output and broad operational bandwidth. The piezoelectric effect is widely used to convert mechanical energy into electrical energy due to its high energy conversion efficiency, ease of implementation, and miniaturization. The review covers various designs, nonlinear methods, optimization techniques, and harvesting materials, with a focus on four promising applications: shoes, pacemakers, tire pressure monitoring systems, and bridge and building monitoring. The paper also discusses the challenges and future directions in energy harvesting, emphasizing the need for reliable and system-integrated solutions. Nonlinear methods, such as bistable and tristable systems, are explored to extend the operational bandwidth and enhance power output. Additionally, the paper reviews new structures and materials that improve power output, including geometry-modified cantilevers, topology optimization, curved structures, electrode optimization, and new structures operating under tension or compression excitations. The goal is to guide future research and promote the practical application of piezoelectric energy harvesters in various fields.